Optical articles such as those used in display devices must meet stringent performance criteria including high light transmissivity, clarity, and ultra-clean appearance. Detrimental to optical performance are defects such as particles, non-planar topography, and disproportionate degree of contact (sometimes referred to as “wet-out”). These defects can be, in part, a result of static charges that are introduced by manufacturing, converting, or assembly processes.
For example, static charges can result from a tape (e.g. masking) or other film that is quickly pulled or peeled away from the target substrate/film during processing. These static charges can subsequently attract particles of dust or other debris that may be near the surface of a film. Particles that eventually land or become anchored on the film can lead to unwanted light blockages, refracting, or absorbance, depending on the film's original purpose. A non-planar topography can be the result of non-uniform shrinkage, warping, or expansion of a film, particularly when an area of the film is pinched or mechanically held in place while movement or creep occurs with another portion of the film. Another cause, however, may be static charges that can create the pinched or stationary area, causing binding between film layers and consequently lead to non-uniform or non-synchronized film changes. The optical defect known as the “wet-out” phenomenon can occur when differences in optical transmission exist between two regions, or when interference patterns such as “Newton's rings” are observed. (The defect is minimally detectable when the wet-out is uniform throughout a film product.) Static charges can contribute to non-uniform attraction of particular areas between two layered films, causing wet-out.
Accordingly, it is desirable to obtain optical articles having improved antistatic properties with little or no detrimental effects on optical performance.